An automatic document feeder used for a facsimile machine, a copier, a printer device, or the like commonly has a shutter mechanism used for overload protection for a conveying roller, alignment of the leading edge of the document, correction of skewing of the document, double-document feed protection, protection of entry of the document, and the like.
An automatic document feeder with a shutter mechanism is disclosed in Japanese Patent Application Laid-Open No. 2005-126202 as shown in FIG. 7A, FIG. 7B, FIG. 8A, and FIG. 8B. FIG. 7A shows a standby state just before the automatic feeding of the document starts and FIG. 7B shows a pick-up state in which the document is picked up. FIG. 8A shows a state in which a cover of the automatic document feeder is opened and FIG. 8B shows a state in which a cover of the automatic document feeder is closed.
This automatic document feeder includes a shutter 109 which is swingably suspended from a cover 102 and a stopper 117 which is provided on a pick-up arm 107 and restricts the movement of the shutter 109. When the pick-up arm 107 is in the standby state shown in FIG. 7A, the stopper 117 makes contact with a receiving portion 113 provided on the shutter 109. Accordingly, the shutter 109 cannot be tilted to a conveyance path 123 side and whereby a position of a leading edge of a document 124 is restricted when the leading edge of the document 124 is brought into contact with the shutter 109.
In the pick-up state shown in FIG. 7B, the pick-up arm 107 is tilted in a direction to make contact with the document 124. By this, the stopper 117 fixed to the pick-up arm 107 is moved below and the contact of the stopper 117 and the receiving portion 113 is released. Accordingly, the shutter 109 can be tilted to the conveyance path 123 side.
Because a pickup roller 116 is provided at an end portion of the pick-up arm 107 on a document tray 112 side, when the pick-up arm 107 is tilted in the clockwise direction, the pickup roller 116 is brought into contact with the document 124 and the document 124 is fed in the conveyance path 123. The document 124 fed in by the pickup roller 116 pushes a restriction piece 119 to the conveyance path 123 side. Whereby, the restriction piece 119 is tilted in the clockwise direction. When the conveyance of the document 124 ends, the restriction piece 119 hangs down by its own weight and additionally, the pick-up arm 107 returns to the original position. Namely, it returns to the standby state shown in FIG. 7A.
By the way, in such mechanism, there is a possibility that the document 124 is jammed. In such case, as shown in FIG. 8A, the cover 102 is opened and the jammed document 124 is removed. FIG. 8B shows a state in which the cover 102 is closed after removing the jammed document.
The automatic document feeder described in Japanese Patent Application Laid-Open No. 2005-126202 has the following problem. When the cover 102 is opened, the pick-up arm 107 returns to a state in which the pick-up arm 107 is not tilted and the restriction piece 119 returns to a state in which the restriction piece 119 hangs down by its own weight. In a state in which the document is jammed, the restriction piece 119 cannot return to the original state completely but the pick-up arm 107 can return to the original state independently of the document jam. Accordingly, the pick-up arm 107 returns to the original state faster than the restriction piece 119 returns to the original state.
As a result, as shown in FIG. 8B, a state in which the receiving portion 113 is located on a left side and the stopper 117 is located on a right side occurs. As easily understood from the comparison of FIG. 7A and FIG. 8B, a positional relation between the receiving portion 113 and the stopper 117 in FIG. 7A is opposite to a positional relation between the receiving portion 113 and the stopper 117 in FIG. 8B. Hereinafter, a state shown in FIG. 8B in which the receiving portion 113 is located on a left side and the stopper 117 is located on a right side is called a reverse state. In the reverse state, the rotation of the restriction piece 119 in counterclockwise direction is restricted because the receiving portion 113 is brought into contact with the stopper 117. As a result, the restriction piece 119 can rotate only in the clockwise direction.
However, when the restriction piece 119 can rotate in the clockwise direction, the position of the leading edge of the document 124 cannot be restricted. For this reason, in the automatic document feeder disclosed in Japanese Patent Application Laid-Open No. 2005-126202, a control and an operation for changing the position of the stopper 117 and the receiving portion 113 are performed separately. When means for performing such control and operation are added, a problem in which the cost of the automatic document feeder increases occurs.